Secondary compression of silty clay adjacent to the Swan River

The Narrows Interchange is constructed on land reclaimed from the Swan River Estuary in Perth, Western Australia. Preconsolidation techniques were used to eliminate primary consolidation and some secondary compression with subsequent settlement resulting from secondary compression.

For projects of this nature, postconstruction settlement can be estimated from the laboratory determined value of C⍺, the coefficient of secondary compression. Postconstruction settlements of the pavements within the interchange have been monitored since the opening in 1973. An analysis of this settlement data has provided field values of C⍺ for comparison with the laboratory determined values.